What you have pictured is a RockChucker II. This picture also shows this name cast into the press frame on the left side. The handle shaft of the RockChucker II is a 5/8's diameter. This means you would use the RCBS Style One adapter. In other words we can fit your press, no fuss, no muss. Here is the link:http://www.bulkreloadingsupply.com/r...momaster-i-ii/
As a side note: Through the many years, RCBS has really only used two sizes, 5/8's and 9/16's handle OD. Most are threaded, some old models are not. We we include an extra lock nut with all RCBS adapters anyway. This allows for the mounting and lock down of the quick release adapter anyway, using one nut on top of the cast and one below effectively "sandwiching" the casting linkage between the nuts.
If your goal is to have a new linkage piece machined or cast to allow for a right and left handle position, I can assure you that the time, hassle and expense of creating this new "one off" part will far out out way the cost of buying a second press. Let me suggest you spend your money a different way and while you save some money, you will avoid the hassles for free. I have found having an extra press to be invaluable for convenience and speed. From our testing, a reloader will never exceed 365 ft lbs of force ....after the mechanical advantage of the press linkage-(in other words at the ram head, to crimp or neck size). This "could" be done with a plastic framed press...which of course no-one would buy. The point being , one does not need a heavy duty press-(read expensive), to crimp or neck size.
There is a "but".... an accurate press is important. Which brings me to the new Breech Lock Technology from Lee or the Lock and Load Tech' from Hornady. Lee's is the least expensive being lower than $75.00 which usually is within the "wife allowed" discretionary buying power of most reloaders. This press is shown here:http://www.bulkreloadingsupply.com/b...allenger-press
Breech Lock tech' while being very fast and convenient for die swaps, more importantly eliminates two nagging variables,
1. depth variance
2. "radial tolerance"
Each time a die swap is made on a traditional press, there is the potential for variance in die "depth" and the lesser known "radial tolerance." This is the "slop" between the male die threads and the female press head nut threads, (without this tolerance/slop, nuts and bolts would not thread together). Your die threads actually "float" within this thread tolerance before you lock it down. This "float" represents "radial variance" which can and will affect your reloads. When cost assessing, keep in mind a separate bushing must be purchased for each die.
I hope this helps.